This invention relates, in general, to remote control transmitters for controlling more than one device or apparatus.
The surge in television-related home entertainment services has given rise to a need to remotely control the various devices or functions. Remote control systems for controlling the functions of a television receiver (TV) have long been known. Recently such systems have come into common use for controlling video cassette recorders (VCRs), raising and lowering projection TV viewing screens, changing the orientation of antennas and controlling operation of TV teletext (Text) services. The requirement of a separate transmitter for each controlled apparatus or device is not only costly and cumbersome, but also confusing to the viewer. A number of schemes have been proposed in the prior art to enable control of more than one device by a single hand-held transmitter. Some merely add additional, complete sets of buttons or keys to the transmitter. Others share keys by incorporating device switches that change the function associated with the individual keys. Many difficulties attend such multiple device remote control transmitters, among them being size, complexity and legibility of indicia applied to multi-function keys.
State-of-the-art home entertainment device remote control transmitters are used with microprocessor-based decoder systems in the controlled apparatus that receives and decodes transmitted signals. The transmitter may, for example, include an integrated circuit for generating bursts of infrared energy in a coded digital format for carrying out different control functions. One such well known system is incorporated in Zenith Model No. SC7000, Part No. 124-79, the circuitry of which is hereby incorporated by reference. Use with different controlled devices is enabled by a mode or device switch for changing the coded signals generated in response to actuation of certain keys. Even in that unit, however, the user must remember to note the position of the device switch to preclude inadvertently activating a wrong function or a wrong device.